ARE SELF-REPORTS OF SMOKING RATE BIASED - EVIDENCE FROM THE 2ND NATIONAL-HEALTH AND NUTRITION EXAMINATION SURVEY

This study determined evidence for digit preference in self-reports of smoking in the Second National Health and Nutrition Examination Surve y (NHANES II). Subject were 4275 adult smokers. Self-reports of smokin g showed a marked degree of digit preference, with the vast majority o f smokers reporting in multiples of 10 cigarettes per day. When number per day was compared to an objective measure of smoking exposure (car boxyhemoglobin; n = 2070) the distribution was found to be significant ly assymetrical. Analysis of the distribution of COHb and various leve ls of number per day indicates that the differences in distribution ar e not due to variability in COHb. Heavier smokers, Caucasians, and tho se with less education were more likely to report a digit preference t han lighter smokers, African-Americans, and those with more education. Results suggest that self-reports of number of cigarettes per day may be biased towards round numbers (particularly 20 cigarettes per day). Implications for assessment of smoking behavior are discussed.